1. Field of the Invention
This invention relates generally to auxiliary vacuum systems for automobiles and, more particularly, to a check valve for controlling the airflow rate through a pump of the auxiliary system.
2. Description of the Prior Art
Auxiliary vacuum systems on some automobiles include engine driven, vane type vacuum pumps which exhaust a mixture of air and lubricating oil into the crankcase of the engine of the vehicle. As long as the integrity of the vacuum system is maintained, the discharge flow rate of the vacuum pump does not exceed the rate at which air in the crankcase is scavenged by the crankcase ventilation system. If the vacuum system integrity is breached, as when a hose upstream of the vacuum pump separates, the discharge of the vacuum pump could exceed the crankcase ventilation scavenge rate and thus pressurize the crankcase. A check valve according to this invention operates when the integrity of the vacuum system is breached to limit the vacuum pump discharge to a level compatible with the crankcase ventilation capacity.